Barrier membranes of self-assembled lamellar poly(lactide-isoprene-lactide) triblock copolymers

Permeation across thin films can be retarded when the films contain aligned flakes of a less permeable material, but aligning these flakes can be difficult. In this research, we measure transport across less permeable flakes which self-assemble from a triblock copolymer. Elasticity is most influenced by an isoprene block but permeability is dominated by a lactide block. The permeability of this lamellar composite for helium, oxygen, and nitrogen is about 20% smaller than that expected from estimates based on resistances in series, implying good alignment. However, the permeability of the triblock is still around 10−7 cm2/s, so that better barriers will require different polymers.